Interrogator and interrogation system employing the same

ABSTRACT

The present invention is directed to an interrogator, method of discerning metal and radio frequency identification (RFID) objects, and an interrogation system employing the same. In one embodiment, the interrogator includes a metal sensing subsystem configured to provide a first signal having a signature representing a presence of a metal object, and a RFID sensing subsystem configured to provide a second signal having a signature representing a presence of a RFID object. The interrogator also includes a control and processing subsystem configured to discern a presence of at least one of the metal and RFID objects from one of the first and second signals.

This application is a continuation of patent application Ser. No.11/357,225, entitled “Interrogator and Interrogation System Employingthe Same,” filed on Feb. 17, 2006, which is a continuation of patentapplication Ser. No. 10/378,043, entitled “Interrogator andInterrogation System Employing the Same,” filed on Mar. 3, 2003, nowU.S. Pat. No. 7,019,650, issued Mar. 28, 2006, which applications andpatent are incorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention is directed, in general, to communication systemsand, more specifically, to an interrogator, method of discerning metaland radio frequency identification (RFID) objects, and an interrogationsystem employing the same.

BACKGROUND OF THE INVENTION

Asset tracking for the purposes of inventory control or the like isemployed in a multitude of industry sectors such as in the foodindustry, apparel markets and any number of manufacturing sectors, toname a few. In many instances, a bar coded tag or radio frequencyidentification (RFID) tag is affixed to the asset and a readerinterrogates the item to read the tag and ultimately to account for theasset being tracked. Although not readily adopted, an analogous systemmay be employed in a medical environment to track equipment such as anElectrocardiogram (EKG) machine or other modular patient monitoringequipment.

Of particular note is a surgical environment in which for preparation ofsurgery a previously sterilized instrument kit of surgical instrumentsand disposable items (collectively referred to as surgical items) isbrought into a surgical suite. The instrument kit contains an assortmentof surgical items including hemostats, clamps, forceps, scissors,sponges, and the like, based on the type of surgery to be performed.Typically, a scrub nurse removes the surgical items from the kit andarranges them on a back table located behind the operating table. Thesurgical items are organized in rows on rolled toweling for ease ofaccess and handling by a surgeon and supporting team. During the courseof a surgical procedure, the surgical items are often positioned on a“Mayo” stand proximate the operating table, while the unused surgicalitems remain on the back table. During the course of and at theconclusion of the surgery, all of the surgical items must be carefullycounted to, among other things, avoid leaving any surgical items in apatient.

In view of the consequences, surgical items are typically counted atleast three times during the course of a surgical procedure. The firstcount is performed prior to the start of the procedure; the second countis performed prior to a closure of the patient; the third count isperformed at the conclusion of the procedure. In many instances such aswhen more than one surgical team is assigned to a procedure, many morecounts of the surgical items, often involving different personnel (e.g.,a circulating nurse and a scrub nurse), are performed. As a matter offact, the Association of PeriOperative Registered Nurses (AORN)advocates four counts of the surgical items as part of its recommendedpractices for surgical procedures. Additionally, to keep track of thecounts of the surgical items, rudimentary systems such as visual recordsscribbled on whiteboards or other more progressive computer tallyingsystems to designate the count of the surgical items are often employed.

In common practice, access to and from an operating room in the surgicalsuite is restricted during the counting process thereby resulting in adetention of valuable professional personnel. A discrepancy in the countmust be resolved by additional counts, physical examination of thepatient or x-ray examination, if necessary. Although it is unusual for adiscrepancy in the count to result from a surgical item remaining in thepatient, counting and recounting occurs in every surgical procedure andthe repercussions associated with the loss of a surgical item is ofgrave concern to a medical facility and the medical professionals.

Thus, the multiple manual counting of surgical items is time consuming,ties up key professional personnel, contributes to surgical suite downtime, distracts personnel from the surgical procedure, lengthens thetime the patient is exposed to anesthesia leading to an increase inmortality and morbidity risk, is generally distasteful to all involved,and still results in errors wherein materials are left in the patient.It should be quite understandable that the average cost overruns of suchdelays associated with the personnel, capital equipment and the surgicalsuite itself can run into the tens of thousands of dollars perprocedure. On an annual basis, the loss of productivity associated withthe surgical suite is quite sizeable and should be addressed to bolsterthe bottom line of a medical facility.

Even with the degree of caution cited above, the problem associated withthe loss of surgical items, especially surgical items retained withinpatients, is a serious one and has a significant influence on the costsof malpractice insurance. As a matter of fact, retained foreign bodieswithin a patient is one of the most prevalent categories of malpracticeclaims and the most common retained foreign body is a sponge. Inaccordance therewith, there is a diagnosis known as “gossypiboma”(wherein gossypium is Latin for cotton and boma is Swahili for place ofconcealment) for the retention of a sponge-like foreign body in apatient. The medical literature is scattered with reports ofpresentations of retained sponges found days, months, or even yearsafter a surgical procedure.

The sponge is typically made of gauze-like material with dimensionsoften covering a four-inch square or a two-inch by four-inch rectangle.At one time sponges were commonly made of cotton, but now a number offilament materials are used. Occasionally, a filament of radiopaquematerial [e.g., barium sulfate (BaSO₄)] is woven into the surgicalsponge. The filament is provided to produce a distinct signature on anx-ray machine for the purpose of determining if a sponge is present inthe patient. While this is generally effective, even these filaments arenot 100% effective in aiding the location of the sponges. Differentresearchers report that x-ray methods to supplement manual counting arefallible.

Moreover, in cases when a sponge remains in the body for a long time,the radiopaque filament can become difficult to locate and may evenconform to internal structures. Some have suggested that a computerizedtomography (CT) scan can be more effective than an x-ray examinationbecause the CT scans and ultrasonography may detect the reduced densityof a sponge and its characteristic pattern of air bubbles trapped withinthe sponge. Many radiologists have published a number of papers over theyears on the problem of finding lost sponges and these are generallyknown in the field of medicine.

As mentioned above, there is a widespread practice in other fields forcounting, tracking and accounting for items and two of the moreprevalent and lowest cost approaches involve various types of bar codingand RFID techniques. As with bar coding, the RFID techniques areprimarily used for automatic data capture and, to date, the technologiesare generally not compatible with the counting of surgical items. Areason for the incompatibility in the medical environment for the barcoding and RFID techniques is a prerequisite to identify items coveredin fluids or waste, and the exigencies associated with the sterilizationof surgical items including a readable tag.

Outside of the surgical suite, the medical community is not unfamiliarwith various forms of automatic identification, counting, and accountingsystems and methods. For example, U.S. Pat. No. 4,164,320, entitled“Patient and Specimen Identification Means and System Employing Same,”to Irazoqui, et al., describes a magnetic encoding technique forpositive identification of patients and specimens associated with aparticular patient. For the most part, Irazoqui, et al. and otherreferences primarily use machine-readable technologies such as barcoding and magnetic stripes. The medical community in general recognizesthat automatic identification, counting, and accounting systems mayreduce errors, improve inventory control and automate record keeping.

For surgical suites and for the purposes of counting surgical items, themedical community has rejected first generation inventory devices, suchas bar coding and RFID techniques, because of a perception that thesolutions have not been adapted to meet the stringent requirements ofthe surgical environment. Contrary to popular understanding, however,the RFID tags including tags employing surface acoustical wavetechnologies may not suffer from many of the perceived limitations.Moreover, the problems which hinder the use of bar coding in thesurgical environment do not have the same implications for RFID tags.

As previously mentioned, familiar applications for RFID techniquesinclude “smart labels” in airline baggage tracking and in many storesfor inventory control and for theft deterrence. In some cases, the smartlabels may combine both RFID and bar coding techniques. The tags mayinclude batteries and typically only function as read only devices or asread/write devices. Less familiar applications for RFID techniquesinclude the inclusion of RFID tags in automobile key fobs as anti-theftdevices, identification badges for employees, and RFID tags incorporatedinto a wrist band as an accurate and secure method of identifying andtracking prison inmates and patrons at entertainment and recreationfacilities. Within the medical field, RFID tags have been proposed fortracking patients and patient files, employee identification badges,identification of blood bags, and process management within thefactories of manufacturers making products for medical practice.

Typically, RFID tags without batteries (i.e., passive devices) aresmaller, lighter and less expensive than those that are active devices.The passive RFID tags are typically maintenance free and can last forlong periods of time. The passive RFID tags are relatively inexpensive,generally as small as an inch in length, and about an eighth of an inchin diameter when encapsulated in hermetic glass cylinders. Recentdevelopments indicate that they will soon be even smaller. The RFID tagscan be encoded with 64 or more bits of data that represent a largenumber of unique identification (ID) numbers (e.g., about18,446,744,073,709,551,616 unique ID numbers). Obviously, this number ofencoded data provides more than enough unique codes to identify everyitem used in a surgical procedure or in other environments that maybenefit from asset tracking.

An important attribute of RFID interrogation systems is that a number oftags can be interrogated simultaneously stemming from the signalprocessing associated with the techniques of impressing theidentification information on the carrier signal. A related anddesirable attribute is that there is not typically a minimum separationrequired between the tags. Using an anti-collision algorithm, multipletags may be readily identifiable and, even at an extreme reading range,only minimal separation (e.g., five centimeters or less) to preventmutual de-tuning is generally necessary. Most other identificationsystems, such as systems employing bar codes, usually impose that eachdevice be interrogated separately. The ability to interrogate aplurality of closely spaced tags simultaneously is desirable forapplications requiring rapid interrogation of a large number of items.

In addition to tracking and accounting for surgical items, a significantrequirement for the management of surgical items involves sterilizationprocedures and processes. One presently employed sterilization processincludes the use of ethylene oxide gas in combination with other gassesat up to three atmospheres of pressure in a special shatterproofsterilization chamber. To achieve effective asepsis levels, this processdemands an exposure of the materials to the gas for one or more hoursfollowed by a twelve hour aeration period. The initial gas exposure timeis relatively long because the sterilization is effected by analkylation of amino groups in the proteinaceous structure of anymicroorganism. Thus, the aforementioned sterilization procedure involvesextended exposure of the item to be sterilized to a reactive atmosphere.

A number of other approaches for performing sterilization have also beenemployed. One such process is high-pressure steam autoclaving. Thisprocess exposes the item to be sterilized to high temperatures and isnot suitable for materials which are affected by either moisture or hightemperature such as corrodible and sharp-edged metals, plastic-madedevices or other devices that may be employed in the medicalenvironment. Other sterilization techniques employ x-ray or radioactivesources. While the x-ray procedure is difficult and expensive, the useof a radioactive source requires expensive waste disposal procedures, aswell as radiation safety precautions. The radiation techniques alsopresent problems because of radiation-induced molecular changes of somematerials which, for example, may render flexible materials such ascatheters or bar coded labels brittle.

Other sterilization approaches have been proposed including surfacetreatment achieved by exposing the medical devices and materials to ahighly reducing gas plasma like that generated by gas dischargingmolecular hydrogen, or to a highly oxidizing gas plasma such as onecontaining oxygen. Depending on the specific sterilization requirements,a mildly oxidizing environment, somewhere between the environmentoffered by oxygen and that offered by hydrogen, is presented by gasdischarging molecular nitrogen, either in a pure state, or inmulti-component mixtures with hydrogen or oxygen, supplemented by aninert gas. In such a manner, plasma discharge chemical-physicalparameters can be adjusted to fit almost any practical application ofsterilization and surface treatment.

While there are a number of other approaches for performingsterilization, the aforementioned discussion demonstrates that a widerange of thermal, chemical, radioactive and other methods are beingemployed and further investigated. Very few identification techniques,labeling techniques or marking techniques are compatible with such awide range of demanding conditions. While a stainless steel instrumentmay be engraved with a form of a readable tag, such techniques areprobably not compatible with disposable items such as sponges.

As alluded to above, RFID tags have been compatible with a number ofarduous environments. In the pharmaceutical industry, for instance, RFIDtags have survived manufacturing processes that require products to besterilized for a period of time over 120 degrees Celsius. Products areautoclaved while mounted on steel racks tagged with a RFID tag such thata rack ID number and time/date stamp can be automatically collected atthe beginning and end of the process as the rack travels through theautoclave on a conveyor. The RFID tags can be specified to withstandmore than 1000 hours at temperatures above 120 degrees Celsius. This isjust one example of how RFID tags can withstand the arduous environmentincluding the high temperatures associated with the autoclave procedure,whereas a bar code label is unlikely to survive such treatment.

Returning to the medical environment, on Apr. 4, 2002, Applied DigitalSolutions, Inc. announced that it received written guidance that theU.S. Food and Drug Administration (FDA) does not consider its RFIDproduct, VeriChip, to be a regulated medical device. The device has beendescribed in the context of a solution for identifying implanted devicessuch as pacemakers. Other examples of RFID tags withstanding demandingenvironments can be seen in the use of such devices for veterinary andanimal husbandry purposes. The RFID tags are used to identify millionsof livestock animals and pets around the world. The systems track meatand dairy animals, valuable breeding stock and laboratory animals. Thetags are typically hermetically sealed and operate over the life of theanimal. Body fluids, temperature, mechanical shock, normalelectromagnetic interference and radiation such as x-rays do not affectthe programmed code within the tag. The tags will not only survive, butwill operate reliably in such environments.

While identification tags or labels may be able to survive the difficultconditions associated with medical applications, there is yet anotherchallenge directed to attaching an identification element to a surgicalitem. The RFID tags are frequently attached to devices by employingmechanical techniques or may be affixed with sewing techniques. A morecommon form of attachment of a RFID tag to a device is by bondingtechniques including encapsulation or adhesion.

While medical device manufacturers have multiple options for bonding,critical disparities between materials may exist in areas such asbiocompatibility, bond strength, curing characteristics, flexibility andgap-filling capabilities. A number of bonding materials are used in theassembly and fabrication of both disposable and reusable medicaldevices, many of which are certified to United States Pharmacopeia ClassVI requirements. These products include epoxies, silicones, ultravioletcurables, cyanoacrylates, and special acrylic polymer formulations.

In many instances, the toughness and versatile properties ofbiocompatible epoxies make them an attractive alternative. Epoxies formstrong and durable bonds, fill gaps effectively and adhere well to mosttypes of substrates. Common uses for medical epoxies include a number ofapplications which require sterilization compatibility such as bondinglenses in endoscopes, attaching plastic tips to tubing in disposablecatheters, coating implantable prosthetic devices, bonding balloons tocatheters for balloon angioplasty, and bonding diamond scalpel bladesfor coronary bypass surgery, to name a few. A wide range of suchmaterials are available and some provide high strength bonds which aretough, water resistant, low in outgassing, and dimensionally stable overa temperature range of up to 600 degrees Fahrenheit. Some epoxies canwithstand repeated sterilization such as autoclaving, radiation,ethylene oxide and cold (e.g., chemical) sterilization methods.

Regarding the counting of surgical items, a variety of holders arepresently available for surgical instruments and disposables items. Inmany cases, the methods for holding the medical items in a manner thatis desirable for transport or for sterilization are combined withconfigurations for displaying the surgical items in such a way thatvisual counting can be performed. For instance, U.S. Pat. No. 3,802,555,entitled “Surgical Instrument Package and Handling Procedure,” toGrasty, et al., discloses a surgical instrument package and handlingprocedure including a set of trays having recessed compartments forsurgical instruments. Grasty, et al. and many other references teachthat counting procedures are performed visually and there is littleflexibility in tailoring the type and number of instruments fordifferent procedures.

Recently, computerized devices have been employed to automatically countthe instruments. The computerized devices, however, are relativelycomplex and expensive such as the surgical count stand described in U.S.Pat. No. 4,943,939, entitled “Surgical Instrument Accounting Apparatusand Method,” to Hoover. To date, these computerized devices require thatthe surgical instruments and disposable items be placed in a certainlocation so that a sensor or vision system can detect the presence or,in some cases, the removal of the instrument. These systems suffer froma number of common shortcomings. For instance, the currently availablesystems do not disclose an apparatus that automatically counts all typesof surgical items, and the systems do not eliminate the time, financialcosts, and risk associated with counting and recounting the surgicalitems to verify the specific identity and location of a missing item.

Accordingly, what is needed in the art is an interrogator, interrogationsystem and related method to identify and account for all types of itemssuch as surgical items in a medical environment that overcomes thedeficiencies of the prior art.

SUMMARY OF THE INVENTION

To address the above-discussed deficiencies of the prior art, thepresent invention provides an interrogator for use in discerning metaland radio frequency identification (RFID) objects. In one embodiment,the interrogator includes a metal sensing subsystem configured toprovide a first signal having a metal signature representing a presenceof a metal object such as a metal instrument, and a RFID sensingsubsystem configured to provide a second signal having a RFID signaturerepresenting a presence of a RFID object such as an object having a RFIDinformation tag. The interrogator also includes a control and processingsubsystem configured to discern a presence of at least one of the metaland RFID objects from one of the first and second signals. In a relatedaspect, the present invention provides a corresponding method ofdiscerning a presence of at least one of metal and RFID objects.

In another embodiment, the present invention provides an interrogatorthat includes a sensing subsystem configured to provide a signal havingat least one of a metal signature representing a presence of a metalobject and a RFID signature representing a presence of a RFID object.The interrogator also includes a control and processing subsystememploying an adaptive integrating filter and configured to coordinate aprocessing of the signal in conjunction with one of an observable anddata to discern a presence of at least one of the metal and RFIDobjects. The data may be located in a database employable by the controland processing subsystem and the interrogator may include a positionsensor configured to provide an interrogator location observable. In arelated aspect, the present invention provides a corresponding method ofdiscerning a presence of at least one of metal and RFID objects.

In another embodiment, the present invention provides an interrogatorthat includes a sensing subsystem configured to provide a plurality ofsignals having at least one of a metal signature representing a presenceof a metal object and a RFID signature representing a presence of a RFIDobject. The interrogator also includes a control and processingsubsystem configured to coordinate a processing of the plurality ofsignals to discern a presence of at least one of the metal and RFIDobjects. The sensing subsystem may provide the plurality of signals inconjunction with multiple scans and the control and processing subsystemmay employ multiscan, coherent signal processing. In a related aspect,the present invention provides a corresponding method of discerning apresence of at least one of metal and RFID objects.

In another aspect, the present invention provides an interrogationsystem that may be employable, without limitation, within a medicalfacility. The interrogation system includes a computer system and atransceiver that transmits and receives signals associated with thecomputer system. The interrogation system also includes an interrogatorhaving a metal sensing subsystem that provides a first signal with ametal signature representing a presence of a metal object, and a RFIDsensing subsystem that provides a second signal with a RFID signaturerepresenting a presence of a RFID object. The interrogator also includesa control and processing subsystem that discerns a presence of at leastone of the metal and RFID objects from one of the first and secondsignals, and a communications subsystem that communicates with thetransceiver.

The foregoing has outlined, rather broadly, preferred and alternativefeatures of the present invention so that those skilled in the art maybetter understand the detailed description of the invention thatfollows. Additional features of the invention will be describedhereinafter that form the subject of the claims of the invention. Thoseskilled in the art should appreciate that they can readily use thedisclosed conception and specific embodiment as a basis for designing ormodifying other structures for carrying out the same purposes of thepresent invention. Those skilled in the art should also realize thatsuch equivalent constructions do not depart from the spirit and scope ofthe invention in its broadest form.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, reference isnow made to the following descriptions taken in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates a diagram of an embodiment of a communication systememployable in a medical environment constructed in accordance with theprinciples of the present invention;

FIG. 2 illustrates a floor plan of an embodiment of a primary medicalfacility that provides an exemplary environment for the application ofthe principles of the present invention;

FIG. 3A illustrates a floor plan of an embodiment of a surgical suitethat provides an exemplary environment for the application of theprinciples of the present invention;

FIG. 3B illustrates a floor plan of the operating room suite of thesurgical suite of FIG. 3A that provides an exemplary environment for theapplication of the principles of the present invention;

FIG. 4 illustrates a pictorial diagram of an embodiment of aninterrogation system employable within an operating room of a medicalfacility and constructed in accordance with the principles of thepresent invention;

FIGS. 5A and 5B illustrate relationship diagrams showing embodiments ofattributes that may be associated with autonomous and integrated modesof operation of an interrogator, constructed in accordance with theprinciples of the present invention;

FIG. 6A illustrates a pictorial diagram of an embodiment of aninterrogation system employable within an operating room of a medicalfacility and constructed in accordance with the principles of thepresent invention;

FIG. 6B illustrates a pictorial diagram of an alternative embodiment ofan interrogation system employable within an operating room of a medicalfacility and constructed in accordance with the principles of thepresent invention;

FIG. 7 illustrates a pictorial diagram of an embodiment of aninterrogator constructed in accordance with the principles of thepresent invention;

FIGS. 8A, 8B and 8C illustrate pictorial diagrams of alternativeembodiments of interrogators constructed in accordance with theprinciples of the present invention;

FIG. 9 illustrates a system diagram of an embodiment of an interrogatorconstructed in accordance with the principles of the present invention;

FIG. 10 illustrates a block diagram of another embodiment of aninterrogator constructed in accordance with the principles of thepresent invention;

FIG. 11 illustrates a system diagram of an alternative embodiment of aninterrogator constructed in accordance with the principles of thepresent invention;

FIG. 12 illustrates a block diagram of another embodiment of aninterrogator constructed in accordance with the principles of thepresent invention; and

FIG. 13 illustrates a block diagram of an embodiment of a control andprocessing subsystem constructed in accordance with the principles ofthe present invention.

DETAILED DESCRIPTION

Referring initially to FIG. 1, illustrated is a diagram of an embodimentof a communication system, generally designated 100, employable in amedical environment constructed in accordance with the principles of thepresent invention. The communication system 100 is configured todistribute, collect and process information across a communicationsnetwork 105 that may include a Local Area Network (LAN), a Wide AreaNetwork (WAN), an Intranet, an Extranet, the Internet, the World WideWeb, the Public Switched Telephone Network (PSTN), future extensions ofthese (e.g., the Internet 2), or a combination thereof. For purposes ofthe present invention, the World Wide Web is defined as all theresources and users on the Internet that are generally using theHypertext Transfer Protocol (HTTP). In one embodiment of the presentinvention, the communication system 100 communicates to each deviceconnected thereto using Transmission Control Protocol/Internet Protocol(TCP/IP).

TCP/IP is a two-layered protocol. The higher layer, Transmission ControlProtocol (TCP), manages the assembling of a message or file into smallerpackets that are transmitted over the communications network 105 andreceived by a TCP layer that reassembles the packets into the originalmessage. The lower layer, Internet Protocol (IP), handles the addresspart of each packet so that it gets to the right destination. Eachgateway computer on the communication system 100 checks the address todetermine where to forward the message. Even though some packets fromthe same message are routed differently than others, the packets will bereassembled at the destination.

TCP/IP uses the client/server model of communication in which a computeruser (a client) requests and is provided a service (such as sending aWeb page) by another computer (a server) in the communication system100. TCP/IP communication is primarily point-to-point, meaning eachcommunication is from one point (or host computer) in the communicationsystem 100 to another point or host computer. TCP/IP and thehigher-level applications that employ TCP/IP are collectively said to be“stateless” because each client's request is considered a new requestunrelated to any previous one (unlike ordinary phone conversations thatrequire a dedicated connection for the call duration). Being statelessfrees the network paths so that everyone can use the paths continuously.It should be understood that the TCP layer itself is not consideredstateless as far as any one message is concerned; the connection remainsin place until all packets in a message have been received.

Internet users are familiar with the even higher layer applicationprotocols that use TCP/IP to get to the Internet. The higher levelapplication protocols include the World Wide Web's Hypertext TransferProtocol (HTTP), the File Transfer Protocol (FTP), Telnet (a command andprotocol that allows users to logon to remote computers), and the SimpleMail Transfer Protocol (SMTP). These and other protocols are oftenpackaged together with TCP/IP.

Personal computer users usually access the Internet through the SerialLine Internet Protocol (SLIP) or the Point-to-Point Protocol (PPP).These protocols encapsulate the IP packets such that the packets can besent over a dial-up phone connection to an access provider's connectiondevice such as a conventional modem.

Protocols related to TCP/IP include the User Datagram Protocol (UDP),the Internet Control Message Protocol (ICMP), the Interior GatewayProtocol (IGP), the Exterior Gateway Protocol (EGP) and the BorderGateway Protocol (BGP). Depending on the circumstance, the UDP may beused instead of TCP for special network communication purposes. Theaforementioned protocols, namely, ICMP, IGP, EGP and BGP, are often usedby network host computers for exchanging router information.

Besides the Internet, TCP/IP may also be employed as the communicationprotocol in the private networks called Intranets and Extranets. AnIntranet is a private network that is contained within an enterprise(such as a organization's office building). The Intranet may consist ofmany interlinked LANs and use leased lines in a WAN. Typically, anIntranet includes connections through one or more gateway computers (notshown) to the outside Internet. The main purpose of an Intranet is toshare organizational information and computing resources amongemployees. An Intranet can also be used to facilitate working in groupsand for teleconferences.

An Intranet typically uses TCP/IP, HTTP and other Internet protocols andin general looks like a private version of the Internet. With tunneling,organizations can send private messages through the public network,using the public network with special encryption/decryption and othersecurity safeguards to connect one part of the Intranet to another.

An Extranet is a private network that uses the Internet protocols andmay use the public network to securely share part of a organization'sinformation or operations with suppliers, vendors, partners, customers,or other medical organizations. An Extranet can be viewed as part of anorganization's Intranet that is extended to users outside theorganization. Just like the Internet, an Extranet also uses HTML, HTTP,SMTP and other Internet protocols.

An Extranet also requires security and privacy provided by the use offirewalls. Firewalls are typically servers that have the ability toscreen messages in both directions so that security is maintained.Firewall servers use digital certificates or similar means of userauthentication, encryption of messages, and the use of virtual privatenetworks (VPNs) that tunnel through the public network.

A medical organization can use an Extranet to exchange large volumes ofdata using Electronic Data Interchange (EDI) and share informationbetween facilities associated therewith. The Extranet can also beemployed to allow an organization to collaborate with otherorganizations on joint development efforts and jointly develop andjointly use training programs. Via the Extranet, an organization canalso provide or access services provided by one organization to a groupof other organizations, such as a medical record management applicationmanaged by one organization on behalf of the medical organization, andshare information of common interest exclusively with partnerorganizations.

Within the medical environment of the communication system 100 is aserver 110 located at a primary medical facility 120 that includessystems that allow the server 110 to receive requests, perform specifictasks, retrieve and update information in at least one database andrespond to requests sent over the communication system 100 to the server110. In other embodiments, the communication system 100 may includemultiple servers, each performing specific tasks, performing the sametasks, acting as redundant systems or acting as database sites.

In another embodiment of the present invention, the server 110 may be anapplication server. An application server is a computer in a distributednetwork containing specialized programs that provide the business logicfor at least one application program located somewhere within thecommunication system 100. The application server is frequently viewed aspart of a three-tier application, consisting of a graphical userinterface (GUI) server, an application (business logic) server, and adatabase and a transaction server. The first-tier of the application,also called “front-end,” is usually located in a client computer such asa personal computer (PC) or a workstation and may include a Webbrowser-based graphical user interface. The second-tier is the businesslogic application or set of applications and can be located on a LAN oran Intranet server.

The third-tier of the application, also called “back-end,” is thedatabase and transaction server and may be located on a mainframe or alarge server. Older, legacy databases and transaction managementapplications are part of the back-end or third-tier. The applicationserver is the middleman between the browser-based front-ends and theback-end databases and legacy systems.

In many instances, the application server is combined with or works witha Web server and is called a “Web application server.” The Web browsersupports an easy-to-create HTML-based front-end for the user. The Webserver provides several different ways to forward a request to anapplication server and to send a modified or new Web page to the user.These approaches include the Common Gateway Interface (CGI), FastCGI,Microsoft's Active Server Page (ASP) and the Java Server Page (JSP). Insome cases, the Web application servers also support request “brokering”interfaces such as CORBA's Internet Inter-ORB Protocol (IIOP).

The communication system 100 also includes conventional personalcomputers (PCs) 125, workstations 130, office computer systems 140 andlaptop computers 150. In other embodiments, the communication system 100may include any number of PCs 125, workstations 130, office computersystems 140 and laptop computers 150. In one embodiment of the presentinvention, the PCs 125, the workstation 130, the office computer system140 and the laptop computers 150 are client computer systems. A clientcomputer system includes a user interface that allows the user to accessinformation, issue requests and perform functions related to the server110. In another embodiment, the office computer system 140 may beconfigured as a second-tier type computer system. For illustrativepurposes only, the PCs 125, the workstation 130, the office computersystem 140 and the laptop computers 150 are located in ones of theprimary medical facility 120, auxiliary medical facility 155 anddoctor's office 160 as shown.

In the illustrated embodiment, the communication system 100 alsoincludes a handheld device 170 such as a personal digital assistant(PDA) or a tablet PC. A PDA is a term used for any small mobilehand-held device that provides, in part, computing, information storageand retrieval capabilities. PDAs are often used for keeping schedules,calendars, address book information and medical information (examples ofPDAs include Hewlett-Packard's Palmtop™ and 3Com's PalmPilot™). A tabletPC is a compact device similar to a laptop computer but with ahandwriting recognition capability (examples of tablet PCs includeCompact TC1000 and ViewSonic V1100).

Most PDAs have a small keyboard and some PDAs have an electronicallysensitive pad on which handwriting can be received and recognized.Apple's Newton™, which has been withdrawn from the market, was the firstwidely-sold PDA that accepted handwriting. Many applications have beenwritten for PDAs including network programs and Internet accessprograms. PDAs are increasingly combined with telephones and pagingsystems for wireless communications. Some PDAs offer a variation of theMicrosoft Windows™ operating system called Windows CE™. Other PDAproducts use a proprietary operating system, such as PalmOS™ or thirdparty operating systems.

An individually addressable vehicle (IAV) 180 such as an ambulance isalso located within the communication system 100. The IAV 180 caninclude any type of vehicle capable of having a computer with a wirelessnetwork receiver and/or transmitter that is individually addressable.For example, an ambulance containing an Internet terminal is an IAV or acomputer with a wireless receiver/transmitter and sensors that transmitspatient information falls within the class of IAVs.

In the illustrated embodiment, the IAV 180 can send requests to theserver 110 within the communication system 100 to request information orperform specific functions, such as retrieving information related tothe location of the vehicle or general patient information. The IAV 180may include a display (not shown) and an input device (not shown) suchas push buttons, a touch screen or a combination of the two tofacilitate user interface therewith.

A mobile telephone 190 may also be included in the communication system100. The mobile telephone 190 includes a display capable of showinginformation retrievable from the communication system 100. The mobiletelephone 190 can send and retrieve information from the server 110 andperform specialized tasks associated with the capabilities of a mobiletelephone with network capabilities. In one embodiment, the mobiletelephone 190 is capable of accessing Web pages, traversing the Internetand displaying information associated with Web pages on its display.

One skilled in the pertinent art should know that the principles of thepresent invention are not limited for use with the types of devicesdescribed above. In other embodiments, the communication system 100 mayinclude individually accessible electronic devices (IAEDs). IAEDs areelectronic devices having a network interface that are individuallyaddressable on a network. For example, medical equipment in a medicalfacility connected to a network having a unique network address isrepresentative of an IAED.

One skilled in the pertinent art should also know that the principles ofthe present invention may be employed via conventional hardwired orwireless communications networks. For instance, a PDA 170 within theprimary medical facility 120 may communicate patient information to theworkstation 130 via a wireless link compatible with a Bluetoothcommunications environment as defined in the Bluetooth Specification,Version 1.1, or an IEEE 802.11 communications environment as defined inthe Institute of Electronic and Electrical Engineers Specification,Section 802.11, both of which are herein incorporated by reference intheir entirety. Of course, other existing or future wirelessspecifications including those employing a proprietary system may alsobe used. The workstation 130 may then download the information to theserver 110 via a hardwired connection. Of course, the networks withinthe medical facilities and the communications network 105 itself mayinclude hardwired and wireless segments. It should also be clear thatthe principles of the present invention are not limited to acommunication system in a medical environment.

For a better understanding of communication systems and networks ingeneral, see “Wireless Communications, Principles and Practice,” byTheodore S. Rappaport, Prentice Hall PTR, 1996, “Microwave MobileCommunications,” edited by William C. Jakes, IEEE CommunicationsSociety, 1993, and “Digital Communications,” 3^(rd) Edition, by John C.Proakis, McGraw-Hill, Inc., 1995, all of which are herein incorporatedby reference in their entirety.

Turning now to FIG. 2, illustrated is a floor plan of an embodiment of aprimary medical facility, generally designated 200, that provides anexemplary environment for the application of the principles of thepresent invention. The primary medical facility 200 includes anemergency room (ER) 210, surgical suite 220, patient rooms 230, retailstores 240, security room 250 and a server room 260. Of course, otherdesignated areas such as a cafeteria may also be located in the primarymedical facility 200.

As mentioned above, the primary medical facility 200 includes acommunications network having hardwired and wireless segments andcommunication devices such as workstations, laptop computers, tabletcomputers and PDAs, to name a few. In conjunction therewith, antennasmay be located in the walls and ceilings of the primary medical facility200 to facilitate wireless communication throughout the facility.Additionally, an interrogation system capable of tracking assets in theprimary medical facility 200 may be located throughout the facilityincluding sensing subsystems proximate the exits. On a grand scale, theinterrogation system including the identification tags affixed to theasset can substantially reduce the risk of losing assets such as modularpatient monitoring equipment. Moreover, the interrogation system may beemployed to track patients bearing an identification tag not only tonote their location, but also their authorization to be in specificlocations and proximate other tagged individuals (e.g., patients, staff,visitors, etc.).

As an example of the applicability of the interrogation system and theadvantages associated therewith, proximate the patient rooms 230 of theprimary medical facility 200 is a storage room 235. Assuming that theassets and supplies associated with the primary medical facility 200include an identification tag, the interrogation system could track thelocation, use, etc. of the assets akin to a supply chain managementsystem. Consequently, not only are the assets and supplies moreeffectively tracked within the primary medical facility 200, but theinventory system may be coordinated with the suppliers to moreefficiently maintain the inventory. Moreover, such an interrogationsystem may be applied to a wide range of applications and environmentssuch as supply chain management systems in retail facilities or securitysystems in airports, to name a few.

For a better understanding of communication systems including antennadesign and communications, etc., see “Antenna Engineering Handbook,” byRichard Johnson and Henry Jasik, McGraw-Hill, Inc., 1992, and “WidebandWireless Digital Communications,” by Andreas F. Molisch, PearsonEducation, 2000, which are herein incorporated by reference in theirentirety.

Turning now to FIG. 3A, illustrated is a floor plan of an embodiment ofa surgical suite, generally designated 300, that provides an exemplaryenvironment for the application of the principles of the presentinvention. The surgical suite 300 includes a pre-operation room 310,waste and sterilization suite 320, an operating room suite 330 and arecovery room 340. The pre-operation room 310 is a location wherein apatient is prepared for a pending surgical procedure. The operating roomsuite 330 includes a plurality of sterile operating rooms wherein thesurgical procedures are performed. Finally, the recovery room 340 is alocation wherein the patient initially recovers following the conclusionof the surgical procedure.

As previously discussed, the surgical items must be thoroughlysterilized and packaged prior to being employed in a surgicalenvironment. The waste and sterilization room 320 is a location withinthe surgical suite 300 wherein the surgical items are sterilizedemploying chemical processes and autoclaving procedures and packaged forthe specific procedures. All surgical items including surgicalinstruments and disposable items must be able to withstand the rigorousprocedures associated with the sterilization process.

This cleaning and decontamination process of non-disposable equipmenttypically consists of several steps. First there is an initial cleaningwhere the equipment is simply hosed off with water. Then, the equipmentwill typically be placed in a washing machine where it is subjected tomultiple steps such as: cleaning via a medical enzymatic detergent andpre-soak, a second cleaning with a low suds detergent and finally aninstrument lubrication cycle. The instruments are then typically removedto a kitting room where each kit is restored to a complete status andplaced into a stainless steel container and a tamper-proof seal isdeployed. There are many different kits for the various types ofsurgical procedures, each requiring a unique set of instruments. Ahospital will typically have to maintain hundreds of different types ofkits and several units of each type. Each one is individually cleanedand inventoried each time. This is very time consuming and laborintensive.

After kitting, the containers proceed to sterilization where multipledifferent types of sterilization procedures may be deployed based on thenature of the equipment. Where possible, high-pressure steam is used, asthis is usually the least expensive approach. However, necessaryinstruments will often require different sterilization procedures suchas, but not limited to, Ethylene Oxide Sterilization, H₂O₂— Plasmasterilization, and Liquid H₂O₂ Sterilization. Of course, the layout ofthe surgical suite 300 and the aforementioned procedures are but oneexample of a surgical suite and related procedures.

Turning now to FIG. 3B, illustrated is a floor plan of the operatingroom suite 330 of the surgical suite 300 of FIG. 3A that provides anexemplary environment for the application of the principles of thepresent invention. The operating room suite 330 includes a core 350 anda plurality of operating rooms (one of which is designated 360). Thecore 350 includes sterile storage to house the instrument kits by typeof surgical procedure. The instrument kits are provided to the operatingrooms 360 through an inner door thereto. A patient enters an outer doorto the operating room 360 wherein a surgical procedure is performed.

As previously mentioned, the surgical items must be counted andaccounted for before, during and following the conclusion of a surgicalprocedure. The presently available systems to track the surgical itemsare laboriously time consuming, costly and in many cases antiquated.Thus, a medical facility can benefit from systems that more efficientlytrack surgical items. The systems may include the communication systemsand networks as noted above as well as identification tags andinterrogation systems that will herein be described. As described abovewith respect to the storage room 235 of the primary medical facility 200of FIG. 2, the interrogation system may assist in the coordination ofthe supply chain management of the surgical items employable within thesurgical suite 300. Again, this type of interrogation system may beemployed in other environments and still realize the benefits associatedtherewith.

Turning now to FIG. 4, illustrated is a pictorial diagram of anembodiment of an interrogation system, generally designated 400,employable within an operating room of a medical facility andconstructed in accordance with the principles of the present invention.In the illustrated embodiment, the interrogation system 400 is employedwithin the operating room having an operating table 402 with a patient403 thereon and a back table 404 that accommodates a plurality ofsurgical instruments 405 a and disposable items 405 b (such as sponges).Other equipment, such as Mayo stands, ring stands, additional backtables and a kick-bucket are also well known to those familiar with theoperating room environment and will also likely be present in somequantity and arrangement. The interrogation system 400 includes acomputer system 410, an operating room transceiver 415 that transmitsand receives signals associated with the computer system 410 and aninterrogator (e.g., a portable interrogator) 425. It should beunderstood that the interrogator may be affixed to a table (e.g., theback table 404), stand, wall or ceiling within a facility and may alsobe embodied in multiple coordinated systems and subsystems, bothhardware and software.

The computer system 410 may operate as a client that is coupled to aserver associated with the medical facility or, alternatively, thecomputer system 410 may be a stand-alone unit solely dedicated to theoperating room 401. The transceiver 415 is coupled between the computersystem 410 and the portable interrogator 425 and is employed to transmitsignals to and receive signals from the portable interrogator 425.

In the illustrated embodiment, the transceiver 415 includes transmit andreceive sections that are coupled through a wired connection 417 to anantenna array having first, second, third and fourth antenna elements416 a, 416 b, 416 c, 416 d located proximate the corners of theoperating room 401. The antenna array may be employed by the transceiver415 to wirelessly communicate with the portable interrogator 425 throughan interrogator antenna 426 included in the portable interrogator 425.The interrogator antenna 426 may be external as shown, or alternatively,it may be integrated into the body of the portable integrator 425. Ofcourse, other antenna configurations including additional or fewerantenna elements or alternate placements may be employed as directed byspecific parameters or characteristics associated with an operating roomenvironment.

The portable interrogator 425 includes a metal sensing subsystem thatprovides a first signal having a metal signature representing a presenceof a metal object and a radio frequency identification (RFID) sensingsubsystem that provides a second signal having a RFID signaturerepresenting a presence of a RFID object. In the illustrated embodiment,the metal sensing subsystem is configured to employ a metal sensinginterface and a metal sensing antenna. Similarly, the RFID sensingsubsystem is configured to employ a RFID sensing antenna interface and aRFID sensing antenna. In an alternative embodiment, the metal and RFIDsensing subsystems are configured to employ an antenna diplexer and anintegrated sensing antenna. Alternatively, the metal and RFID sensingsubsystems may be integrated into a sensing subsystem that provides asignal or a plurality of signals having at least one of a metalsignature representing a presence of a metal object and a RFID signaturerepresenting a presence of a RFID object.

The portable interrogator 425 also includes a control and processingsubsystem that discerns a presence of at least one of the metal and RFIDobjects from one of the first and second signals. The control andprocessing subsystem may also coordinate a processing of the signal(s)from the sensing subsystem to discern a presence of at least one of saidmetal and RFID objects. The control and processing subsystem may alsoemploy an adaptive integrating filter and coordinate a processing of thesignal(s) in conjunction with one of an observable and data to discern apresence of at least one of the metal and RFID objects. The portableinterrogator 425 also includes a communications subsystem, coupled tothe interrogator antenna 426, that allows communication with thetransceiver 415. The portable interrogator 425 further includes aninternal user interface 427 and an external user interface 428 that iscoupled to the computer system 410, in the illustrated embodiment. Theportable interrogator 425 still further includes a position sensor thatallows a position of the portable interrogator 425 to be determined. Theportable interrogator 425 may also have a wired interface, for example,a Universal Serial Bus (USB) port.

Prior to starting a surgical procedure, the portable interrogator 425may be employed to inventory the plurality of surgical instruments 405 aand disposable items 405 b in the operating room 401. This may beaccomplished by scanning the plurality of surgical instruments 405 a anddisposable items 405 b with the portable interrogator 425, beforesurgery begins. Alternatively, a separate asset management system mayprovide this information to the portable interrogator 425. Verificationof the inventory may employ both approaches. In addition, the presenceof a particular kind of surgical instrument 405 a may be verifiedthrough the scanning action as was requested by a medical professional.The request may have been arranged through the computer system 410 orthrough a medical professional's PDA. During the surgical procedure, theportable interrogator 425 may be employed to monitor any movement orrepositioning of the plurality of surgical instruments 405 a anddisposable items 405 b thereby providing location tracking during use ofany of the items in the surgical procedure.

Additionally, the portable interrogator 425 may be employed to scan thepatient 403 before, during or after closing the surgical procedure.Scanning the patient 403 before the surgical procedure provides locationof metal or RFID objects already present in the patient 403. Scanningthe patient 403 during the surgical procedure provides a real-time,operational assurance that the location of the plurality of surgicalinstruments 405 a and disposable items 405 b are where they are intendedto be. Scanning the patient 403 after concluding the surgical procedureprovides a verification that any metal or RFID objects remaining areonly those intended. In addition, the portable interrogator 425 may makemultiple scans about the patient 403 to further assist in ascertaining alocation of any metal or RFID objects.

The portable interrogator 425 may be employed in either an autonomous oran integrated mode of operation. In the autonomous mode of operation,the control and processing subsystem autonomously accomplishes theoperation of the portable interrogator 425, provides all analysisalgorithms and performs all functions needed to discern the presence ofmetal and RFID objects that have been scanned by the portableinterrogator 425. Alternatively, the integrated mode of operationemploys the computer system 410, either wirelessly via the transceiver415, the antenna array and the interrogator antenna 426 or through thewired interface, to support the control and processing subsystem indiscerning the presence of metal and RFID objects. The integrated modemay provide for a greater selection of sensors and sensed items that maybe integrated into an enhanced solution. The integrated mode typicallyallows a more extensive utilization of databases and algorithms to beemployed than in the autonomous mode of operation.

The majority of moveable metal objects employed in the operating room401 are typically surgical instruments or sharps of various sizes andshapes or metal structures intended to be surgically implanted in thepatient 403. Other metal objects may include disposable spongesemploying a metal wire that allows their detection by the metal sensingsubsystem. Each of the metal objects generates a metal signature thatallows its detection by the portable interrogator 425. Generally, themetal signature may cause its associated first signal to posses auniversal characteristic, such as a shape, an amplitude or a frequencyspectrum, that indicates metal is present. More specifically, the metalsignature may cause the first signal to possess a particularcharacteristic that is substantially unique to a particular type ofmetal object thereby allowing a more unique identification.

RFID signatures differ from metal signatures in that the RFID signature,associated with the second signal, is unique and independent of a shapeor a size of the RFID object. The RFID signature is normally provided bya RFID tag (e.g., a RFID information tag including data thereon) appliedto the object. If a RFID tag were applied to a surgical metalinstrument, for example, the portable interrogator 425 would recognize aunique RFID signature as well as the metal signature that may be generalor specific to the surgical metal instrument. The metal signature may beused to discern that an object is a metal object, or that it is a typeof surgical metal instrument. However, the RFID signature may be used todiscern exactly which surgical metal instrument the metal object is.Additionally, RFID tagging of disposable items, such as sponges, mayprovide a unique RFID signature for each item, whereas disposable itemsincorporating only a metal wire may typically provide a metal signaturespecific to all such items.

The internal user interface 427 typically includes an integral displayemploying alphanumeric or graphical characters and a touchpad forentering data or information. The internal user interface 427 may alsoemploy audible or visual alarms. In the illustrated embodiment, theexternal user interface 428 includes a monitor 428 a and a keyboard 428b that are wirelessly coupled to the portable interrogator 425 and thecomputer system 410. Alternatively, the wired interface of the portableinterrogator 425 may be employed to couple the external user interface428 to the portable interrogator 425. The external user interface 428may provide a more extensive data entry capability while facilitating abroader monitoring capability than may be provided by the internal userinterface 427.

Position monitoring of the portable interrogator 425 is provided by theposition sensor, which allows a relative determination of its positionwith respect to the patient 403, the back table 404 or another location.RFID position markers may be placed on the patient 403 at predeterminedbenchmark positions, such as the nose, navel, knee and ankle, to providesubstantially unique patient dimensions (or a location of a feature of apatient) and allow other patient attribute positions and metrics to bemore accurately determined. Additionally, RFID/metal calibration markersmay be positioned at other locations on the patient 403 to allow theportable interrogator 425 to calibrate depths or other appropriatethicknesses associated with the patient 403. Of course, RFID markers maybe placed on items such as the back table, ring stand, the Mayo stand orany other location within the operating room deemed appropriate.

A plurality of the portable integrators 425 may be coupled togethermechanically or electrically, either wirelessly or through their wiredinterfaces, to form a networked-interrogator mode of operation. Thenetworked-interrogator mode of operation allows two or moreinterrogators to share and collaborate data. This collaboration mayinclude the coordination of a plurality of interrogators simultaneouslyemployed on the patient 403. Alternatively, the collaboration may alsoinclude coordinating information associated with the operating room 401,such as information associated with items on the back table 404, as wellas other pertinent information located within the medical facilityenvironment. This collaborative effort may occur in real time or over aperiod of time and may employ the interrogators operating in anautonomous mode, an integrated mode or a combination of the modes.

Turning now to FIGS. 5A and 5B, illustrated are relationship diagrams,generally designated 500 and 550 respectively, showing embodiments ofattributes that may be associated with autonomous and integrated modesof operation of an interrogator, constructed in accordance with theprinciples of the present invention. In the illustrated embodiment, therelationship diagram 500, associated with the autonomous or nominalsensitivity mode of operation, employs a metal system 505 and a RFIDsystem 510 as inputs. The metal system 505 provides metal sensing 506and metal control and processing 507. The RFID system 510 provides RFIDsensing 511 and RFID control and processing 512.

The metal system 505 may be used to detect a presence and a generallocation of metal objects within a patient. Similarly, the RFID system510 may be used to detect a presence and a general location of objectswithin the patient that employ RFID tags. Then, an interrogator detectedobject 515 provides an indication of these detected metal or RFIDobjects, and an interrogator reporting 520 provides a representation ofthis detection. When the interrogator detected object 515 is combinedwith an interrogator location (e.g., operator-determined interrogatorlocation) 525, a determined object and location (e.g.,operator-determined object and location) 530 may be provided employingthe interrogator operating in an autonomous mode.

The relationship diagram 550 of FIG. 5B, associated with the integratedor enhanced mode of operation, employs an expanded plurality of inputsas compared to the autonomous mode of operation. In the illustratedembodiment, this plurality of inputs includes metal sensing 552, RFIDsensing 554, interrogator location observables 556, RFID positionmarkers 558, RFID/metal calibration markers 560, a patientdemographics/history database 562, anatomical databases 564,evidence-based medicine databases 566 and RFID and metal objectsignature databases 568.

An adaptive integrating filter 570 processes these inputs to provide aresulting interrogator detected object and location 575. Theinterrogator detected object and location 575 allows an integratedinterrogator reporting 580, which is typically more comprehensive thanthe autonomous mode of operation. An optional remote display of objectdetection and location 581 allows enhanced object display and locationpresentations. An adaptive signal strength and signal capability 585employs a feedback path 586 to the adaptive integrating filter 570 toallow extended object detection and location enhancement.

The integrated mode of operation allows the incorporation of real time,adaptive characteristics that may be based on specific patientattributes or specific anatomical locations being scanned at anyspecific time. The integrated mode of operation may employ multiscan,coherent signal processing of diverse multiple inputs to achievesignificantly higher detection sensitivities thereby allowing moreprecise object location and identification. The adaptive integratingfilter 570 may be a single adaptive filter, such as a Kalman filter, orit may be more complex to meet a specific patient situation.

A more precise location of the interrogator may be afforded byintegrating an instantaneous output of an internal inertial positionsensor with RFID position markers 558 placed at predetermined anatomicallocations on the patient. RFID/metal calibration markers 560 typicallyplaced at other specific patient locations, where an associated amountof “body-masking” will occur, allows tailoring of the RFID and metaldetection responses for specific patient requirements.

Integrating information from databases allows an additional degree ofenhancement. The patient demographics/history database 562 may providepatient specific information such as height, weight, age, ethnicity,medical history and past surgeries as well as distinctive foreignobjects known to be present such as screws, pins, artificial joints,etc. The anatomical databases 564 may be correlated to specific patientinformation to provide anatomy information that is generally applicableto the demographics of the patient or specifically applicable to thehistory of the patient. The evidence-based medicine databases 566, suchas Cochrane or Best Evidence, may provide conscientious, explicit andjudicious use of current best evidence in making clinical decisionsabout the care of individual patients.

The RFID and metal object signature databases 568 may provide a catalogof RFID tag numbers that are pertinent to a specific operating room ormedical facility environment. Similarly, a catalog of metal objectsignatures that are pertinent to the metal objects employed in theoperating room or medical facility may also be provided.

These databases typically exist external to the interrogator. In fact,many of the databases may exist at diverse worldwide locations that areaccessible through private networks or through the Internet. The signalprocessing that allows integration of these plurality of inputs may alsobe external to the interrogator wherein it provides metal sensing, RFIDsensing and position information for external integrated processing.Then, the signal processing result may be provided for display to anintegral user interface or to an external user interface associated withthe interrogator. Thus, a control and processing subsystem of aninterrogator may employ an adaptive integrating filter and coordinate aprocessing of a signal from a sensing subsystem in conjunction with theobservables or the data as herein described to discern a presence of atleast one of metal and RFID objects.

Turning now to FIG. 6A, illustrated is a pictorial diagram of anembodiment of an interrogation system, generally designated 600,employable within an operating room of a medical facility andconstructed in accordance with the principles of the present invention.In the illustrated embodiment, the interrogation system 600 is employedwithin an operating room having an operating table 602 with a patient603.

The interrogation system 600 includes a computer system 610 coupled to adatabase 611, a transceiver 615 that transmits and receives signalsassociated with the computer system 610 employing a transceiver antenna616 and an interrogator (e.g., a portable interrogator) 625 employing aninterrogator antenna 627. The interrogation system 600 also includesfirst, second, third and fourth RFID position markers 630, 631, 632,633, (collectively referred to as RFID position markers 630-633), a RFIDpatient bracelet 640 attached to the patient 603 and first, second,third and fourth RFID/metal calibration markers 641, 642, 643, 644,(collectively referred to as RFID/metal calibration markers 641-644).

The RFID position markers 630-633 may be placed at predeterminedlocations on the patient 603. Generally, RFID position markers provide“position-unique” mapping of the patient 603 wherein the mapping mayemploy more or less RFID position markers than those shown in FIG. 6A.When used in conjunction with a sweeping motion of the portableinterrogator 625, it may be possible to specifically identify thepresence of a metal or a RFID tagged object as being located between twoof the RFID position markers. Thus, a control and processing subsystemof the portable interrogator may employ multiscan, coherent signalprocessing to coordinate a processing of a plurality of signals (e.g.,resulting from multiple scans) from a sensing subsystem to discern apresence of at least one of metal and RFID objects.

Additionally, employing an inertial position sensor in the portableinterrogator 625 allows a more precise determination of the presence andlocation of a RFID or metal object between these two RFID positionmarkers. In this instance, it may be possible to integrate sensor dataacross multiple sweeps of the portable interrogator 625 therebyincreasing its sensitivity and quality of detection (e.g., by 30 times).Of course, any number of RFID position markers may be employed andpositioned as appropriate to a particular situation.

The RFID/metal calibration markers 641-644 have unique RFID signaturesand known amounts and types of metal. They are typically not placed ontop of the patient 603, but are placed beneath or on the side of thepatient 603, such as the underside of a leg or between an arm and thechest. As the portable interrogator 625 is swept over the patient 603,the RFID/metal calibration markers 641-644 are used to calibrate thetype and sensitivity of interrogation needed by the portableinterrogator 625 to provide an acceptable level of object identificationthereby achieving an integrity of operation. Of course, any number ofRFID/metal calibration markers may be employed and positioned asappropriate to a particular situation. Alternatively, calibrationmarkers may be employed that use only RFID or only metal as appropriateto a particular application.

The RFID patient bracelet 640 contains specific information pertainingto the patient 603. The RFID patient bracelet 640 is read, either by theportable interrogator 625 or another appropriate device. The specificinformation may then be applied by the portable interrogator 625 or thecomputer system 610 for the purpose of further improving measurementsensitivity and quality. For example, ample interrogation for a sevenyear old female patient weighing 40 pounds may be quite different fromthat of a 50 year old male patient weighing 260 pounds. Identifying thepatient 603 as well as employing specific databases and generalinformation associated with the patient 603 allows for measurementquality and sensitivity improvements. The computer system 610 employingthe database 611 may be employed in an integrated mode of operation orthe portable interrogator 625 may operate autonomously.

Turning now to FIG. 6B, illustrated is a pictorial diagram of analternative embodiment of an interrogation system, generally designated650, employable within an operating room of a medical facility andconstructed in accordance with the principles of the present invention.In the illustrated embodiment, the interrogation system 650 is employedwithin an operating room having an operating table 652 with a patient653.

The interrogation system 650 includes a computer system 660 coupled to adatabase 661, a medical facility server 670 coupled to extendeddatabases 671 and an external user interface 678 employing a monitor 678a and a keyboard 678 b, a transceiver 665 employing a transceiverantenna 666 that transmits and receives signals associated with thecomputer system 660 and the medical facility server 670. Theinterrogation system 650 also includes an interrogator (e.g., a portableinterrogator) 675 employing an interrogator antenna 677 thatcommunicates with the transceiver 665, first, second, third and fourthRFID position markers 680, 681, 682, 683, a RFID patient bracelet 640attached to the patient 653 and first, second, third and fourthcalibration markers 691, 692, 693, 694.

As was discussed above, the database 661 and extended databases 671 mayprovide additional information and algorithms to be used as part of theinterrogating process. Not only is patient-specific informationavailable, but statistical information, relevant to patient types mayalso be available. This information may be employed for extensive signalprocessing within the medical facility server 670, or subsets of thisinformation may be used for signal processing within the computer system660 or the portable interrogator 675 itself. Additionally, the externaluser interface 678, an integral display associated with the portableinterrogator 675 or both may be employed in the interrogating process.

Turning now to FIG. 7, illustrated is a pictorial diagram of anembodiment of an interrogator (e.g., a portable interrogator), generallydesignated 700, constructed in accordance with the principles of thepresent invention. The portable interrogator 700 includes an electronicshousing 705 having a display 706, a touch pad 707 employing a collectionof touch keys 708 and an audible alarm 709. The portable interrogator700 also includes a sensing antenna assembly 710, a handle 715 and aninterrogator antenna 720.

The sensing antenna assembly 710 contains RFID and metal sensingantennas and antenna interfaces that may be employed to sense RFID andmetal objects associated with, for instance, a patient in a medicalenvironment. The electronics housing 705 contains a metal sensingsubsystem, a RFID sensing subsystem, a control and processing subsystemand a communications subsystem. The metal sensing subsystem and the RFIDsensing subsystem accept RFID and metal antenna signals, respectively,and are coupled to the control and processing subsystem for signalprocessing that results in the detection of RFID and metal objects, whenpresent. Again, the metal and RFID sensing subsystems may be integratedinto a sensing subsystem. The control and processing subsystem iscoupled to the communications subsystem, which employs the interrogatorantenna 720 to communicate with external computer systems, databases anddisplays. The display 706, the touch pad 707 and the audible alarm 709provide an integral user interface for the portable interrogator 700.

Turning now to FIGS. 8A, 8B and 8C, illustrated are pictorial diagramsof alternative embodiments of interrogators (e.g., portableinterrogators), generally designated 800, 825 and 850, respectively,constructed in accordance with the principles of the present invention.FIG. 8A illustrates the portable interrogator 800 showing a top view 805and a side view 810 positioned above, for instance, a patient 815.

In the illustrated embodiment, an antenna assembly 820 is configured toprovide spatial information related to the location of RFID and metalobjects located within or proximate the patient 815. This may beaccomplished employing the direct geometry of the antenna assembly 820.The antenna assembly 820 is configured to contour the patient 815, asshown, and consists of multiple smaller antenna elements spacedcontiguously within the antenna assembly 820 (not shown). In this way, asensed RFID or metal object is also sensed by a specific antenna elementwithin the antenna assembly 820. The location of that specific antennaelement provides information relative to a corresponding location on thepatient 815. The illustrated embodiment of FIG. 8A depicts a generaldesign concept of the invention and other embodiments employing theseconcepts are also possible.

FIG. 8B illustrates an embodiment of a portable interrogator 825, whichis configured to be a mitten that may be worn, for instance, on a healthcare individual's hand. FIG. 8B includes a top view 830 and a side view835 of the portable interrogator 825. Employing this mitten-likeembodiment, the health care individual may move his/her hand over thepatient to obtain specific locations of metal and RFID tagged objectsbased on the location of his/her hand. FIG. 8B is intended to illustratethe concept of incorporating a portable interrogator into a glove ormitten-like configuration, and of course, other embodiments employingthis basic concept are also well within the scope of the presentinvention.

FIG. 8C illustrates a portable interrogator 850 showing a top view 855and a side view 865 positioned above, for instance, a patient 870. Thetop view 855 illustrates an expanded display 856 employing a relativelylarge “paddle-like” configuration. The illustrated embodiment consistsof an antenna assembly having an array of antenna elements on thepatient-side and a corresponding expanded display capability on theuser-side. The expanded display capability consists of a display grid,which conforms to the antenna elements in a one-to-one manner. An objectsensed through a specific antenna element of the antenna assembly causesa sensed output to occur on its specific and corresponding portion ofthe expanded display.

This embodiment provides additional spatial information of the detectedobjects with respect to the patient. The illustrated embodiment depictsa means of mapping specific antenna elements to a corresponding display.Of course, other embodiments employing this principle of having aone-to-one mapping of antenna elements and displays are well within thebroad scope of the present invention. Also, while the interrogators havebeen described in relation to a medical environment, one skilled in theart should understand that the interrogator may be employed in otherenvironments and still be within the broad scope of the presentinvention.

Turning now to FIG. 9, illustrated is a system diagram of an embodimentof an interrogator, generally designated 900, constructed in accordancewith the principles of the present invention. The interrogator 900includes a metal sensing subsystem 905, a metal sensing antennainterface 906, a metal sensing antenna 907, a RFID sensing subsystem910, a RFID sensing antenna interface 911, a RFID sensing antenna 912, acontrol and processing subsystem 915, a communications subsystem 925, aninternal user interface 930, a position sensor 935 and a power source940.

In the illustrated embodiment, the internal user interface 930 includesa touchpad 931, an integral display 932 and an alarm 933, which mayinclude both an audible alert 933 a and a visual alert 933 b.Additionally, the interrogator 900 employs an external user interface934, coupled through the communications subsystem 925, as shown. Theexternal user interface 934 may employ substantially similar elements asthe internal user interface 930. However, the display and touchpadelements may be larger and more extensive in capability.

The metal sensing subsystem 905 is coupled to the metal sensing antennainterface 906 and the metal sensing antenna 907 and is configured toprovide a first signal having a signature representing a presence of ametal object. The RFID sensing subsystem 910 is coupled to the RFIDsensing antenna interface 911 and the RFID sensing antenna 912 and isconfigured to provide a second signal having a signature representing apresence of a RFID object. The control and processing subsystem 915 iscoupled to the metal sensing subsystem 905 and the RFID sensingsubsystem 910 and is configured to discern a presence of at least one ofthe metal and RFID objects from one of the first and second signals.

The control and processing subsystem 915 coordinates an operation of themetal sensing subsystem 905 and the RFID sensing subsystem 910.Additionally, the control and processing subsystem 915 analyzes thefirst signal for a metal object signature and the second signal for aRFID object signature. The metal object signature typically may becreated by a change or distortion in a field associated with the metalsensing subsystem 905. The RFID object signature typically may becreated as an identification data sequence associated with a RFIDobject. Analysis of the first and second signals may employ signatureparameters based on factors such as a size, a shape, an orientation,likelihood, a position or a depth associated with the metal object orthe RFID object. Additionally, the analysis may employ data associatedwith metal and RFID objects that is internally or externally stored.

The control and processing subsystem 915 is also coupled to thecommunications subsystem 925, the internal user interface 930 and theposition sensor 935. The position sensor 935 may typically be of aninertial type and may provide either two dimensional (2D) or threedimensional (3D) information as to the position of the interrogator 900for the purpose of aiding metal or RFID tag detection. In theillustrated embodiment, the communications subsystem 925 employstransmit and receive circuitry coupled to an antenna to exchange datawith an external transceiver.

For example, the communications subsystem 925 may be employed to sendmetal and RFID signature information to an external server for a moreextensive analysis that may be beyond the capability of the control andprocessing subsystem 915. The results of the analysis may be returnedthrough the communications subsystem 925 for final disposition by thecontrol and processing subsystem 915. Alternatively, the control andprocessing subsystem 915 may employ the communications subsystem 925 tosequentially query external databases for signature profiles or analysisalgorithms to be applied locally by the control and processing subsystem915.

The internal user interface 930 allows a user to interact with theinterrogator 900 to provide input and receive output associated with itsapplication. The position sensor 935 cooperates with the control andprocessing subsystem 915 to allow a position of the integrator 900 to bedetermined. The power source 940 employs a rechargeable or replaceablebattery and provides necessary operating supply voltages to theinterrogator 900.

The user of the interrogator 900 may employ the touchpad 931 to select amode of operation or both enter and request information about a specificmetal or RFID object. The integral display 932 may be employed to show aRFID number or indicate that the interrogator 900 is detecting thepresence of a metal or RFID object. Alternatively, the external display934 may be employed to indicate the presence of a metal or RFID object.Additionally, the integral display 932 or the external display 934 maybe employed in conjunction with the position sensor 935 to determine aprofile and a position of the metal or RFID object with respect to amovement or sweeping motion of the interrogator 900. The audible alert933 a may include distinctive tones or synthesized voice communications.The visual alert 933 b may be flashing or colored features that includetextual or graphical representations. The visual alert 933 b may beassociated with the integral display 932, the external display 934, orthey may be stand-alone.

Turning now to FIG. 10, illustrated is a block diagram of anotherembodiment of an interrogator, generally designated 1000, constructed inaccordance with the principles of the present invention. Theinterrogator 1000 includes a metal sensing subsystem 1005, a metalsensing antenna interface 1010, a metal sensing antenna 1015, a RFIDsensing subsystem 1020, a RFID sensing antenna interface 1030, a RFIDsensing antenna 1035 and a control and processing subsystem 1040.

The metal sensing subsystem 1005 includes a metal sensingdigital-to-analog converter (DAC) 1006, a metal sensing transmitamplifier 1007, a metal sensing receive amplifier 1008 and a metalsensing analog-to-digital converter (ADC) 1009. The metal sensingantenna interface 1010 includes a metal sensing transmit conditioningfilter 1011 and a metal sensing receive conditioning filter 1012. Themetal sensing antenna 1015 includes a metal sensing transmit antenna1016 and a metal sensing receive antenna 1017.

The RFID sensing subsystem 1020 includes a RFID sensing DAC 1021, a RFIDsensing transmit selector switch 1022, a first RFID sensing transmitamplifier 1023, a second RFID sensing transmit amplifier 1024, a firstRFID sensing receive amplifier 1025, a second RFID sensing receiveamplifier 1026, a RFID sensing receive selector switch 1027 and a RFIDsensing ADC 1028. The RFID sensing antenna interface 1030 includes firstand second RFID sensing transmit conditioning filters 1031, 1032 andfirst and second RFID sensing receive conditioning filters 1033, 1034.The RFID sensing antenna 1035 includes first and second RFID sensingtransmit antennas 1036, 1037 and first and second RFID sensing receiveantennas 1038, 1039. “HI band” and “LO band” capabilities are present toaccommodate the wide frequency range necessary to detect the varioustypes of RFID tags.

In an alternative embodiment, a mixing or heterodyning function may beincluded within the RFID sensing ADC 1028 or the RFID sensing DAC 1021functions. These techniques are known to those skilled in the pertinentart and may be employed to translate signal processing to a moredesirable frequency range thereby allowing less expensive or morereadily available components to be used. Additionally, the specificnature and function of the first and second transmit conditioningfilters 1031, 1032 and first and second RFID sensing receiveconditioning filters 1033, 1034 may vary depending on the specificalgorithms employed for control and processing and for signal generationand recovery. Also, some embodiments may not require some or all of thefilters shown.

In the illustrated embodiment, the control and processing subsystem 1040may be a software defined structure that allows features and functionsof the interrogator 1000 to be easily modified or tailored by alteringsoftware functions. The control and processing subsystem 1040 employs acrystal oscillator to provide a precise frequency reference for both themetal and RFID sensing subsystems 1005, 1020. Operation of the controland processing subsystem 1040 will be more fully discussed with respectto FIG. 13, below.

The control and processing subsystem 1040 generates a metal sensingdigital excitation signal based on a metal sensing mode of operationselected and provides this signal to the metal sensing DAC 1006. Themetal sensing digital excitation signal may be in the form of acontinuous tone. Alternatively, the digital excitation signal may varyin amplitude, frequency, or phase and may also be of a pulsed naturewherein the waveform duty cycle is less than 100 percent. The frequencyof the metal sensing digital excitation signal may generally be in therange of five to 100 kHz. Different waveforms may be used to optimize adetection of both ferrous and non-ferrous metals. These waveforms may beselected for different sizes and masses of metals and for metals atdifferent locations and depths within a patient. Algorithmic informationemployed in generating these excitation signals may be part of thecontrol and processing subsystem 1040.

The metal sensing DAC 1006 converts the metal sensing digital excitationsignal into an analog signal that, except for its amplitude, is themetal sensing transmit signal. The analog signal is provided to themetal sensing transmit amplifier 1007, which amplifies the analog signalto a correct amplitude for transmission. The output of the metal sensingtransmit amplifier 1007 is provided to the metal sensing transmitconditioning filter 1011, which sufficiently attenuates all out-of-bandsignals and provides a proper impedance match to the metal sensingtransmit antenna 1016. The metal sensing transmit antenna 1016 launchesthe metal sensing transmit signal.

A metal object present in the vicinity of the metal sensing transmitantenna 1016 and the metal sensing transmit signal will generate a metalsensing return signal wherein the metal sensing return signal may bebased on a change in a field characteristic of the metal sensingtransmit signal. The field characteristic may be altered in the vicinityof the metal object such that a distinctive metal sensing receive signalimpinges on and excites the metal sensing receive antenna 1017. Theoutput of the metal sensing receive antenna 1017 is provided to themetal sensing receive conditioning filter 1012, which sufficientlyattenuates all out-of-band energy and provides a proper impedance matchbetween the metal sensing receive antenna 1017 and the metal sensingreceive amplifier 1008.

The metal sensing receive amplifier 1008 amplifies the metal sensingreceive signal to a level sufficient for processing and provides it tothe metal sensing ADC 1009. The metal sensing ADC 1009 provides a metalsensing digital signal, proportional to the metal sensing receivesignal, to the control and processing subsystem 1040, which determinesif the metal sensing digital signal has a signature representing apresence of a metal object in the vicinity of the metal sensing antenna1015.

The control and processing subsystem 1040 generates a RFID sensingdigital excitation signal based on a RFID mode of operation selected andoutputs this signal to the RFID sensing DAC 1021. The RFID sensingdigital excitation signal may be in the form of a code that excites andenergizes a RFID object present such as a RFID tag. The carrierfrequency associated with this code may be in one of two frequencybands. A first frequency band may be centered around 133-135 kHz and isdesignated as the “LO band”. A second frequency band may be centeredaround 10-13 MHZ and is designated the “HI band”. Alternatively, a “HIband” around 902-928 MHZ may also be employed. Alternatively, the133-135 kHz and the 10-13 MHZ bands may be combined in the “LO band” andsome specific implementations may require only a single band. Afrequency band is selected based on the RFID mode of operation selected.Each frequency band corresponds to different types of RFID tags present,which may be based on its size or other factors. Generally, algorithmicinformation to generate the RFID sensing digital excitation signal iscontained in the control and processing subsystem 1040.

The RFID sensing DAC 1021 converts the RFID sensing digital excitationsignal into an analog signal that, except for amplitude, is the RFIDsensing transmit signal. The RFID sensing transmit signal is provided tothe RFID sensing transmit selector switch 1022, which is controlled bythe control and processing subsystem 1040. The RFID sensing transmitselector switch 1022 directs the RFID sensing transmit signal to thefirst RFID sensing transmit amplifier 1023 or the second RFID sensingtransmit amplifier 1024, respectively, based on whether the RFID sensingtransmit signal is “HI band” or “LO band.” The first RFID sensingtransmit amplifier 1023 and the second RFID sensing transmit amplifier1024 increase the amplitude of the “HI band” and “LO band” signals to acorrect amplitude for transmission.

The first RFID sensing transmit amplifier 1023 provides the “HI band”signal to the first RFID sensing transmit conditioning filter 1031 andthe second RFID sensing transmit amplifier 1024 provides the “LO band”signal to the second RFID sensing transmit conditioning filter 1032. Thefirst and second RFID sensing transmit conditioning filters 1031, 1032employ differing center frequencies and sufficiently attenuateassociated out-of-band signals. Additionally, they provide a properimpedance match to their respective first or second RFID sensingtransmit antennas 1036, 1037, which launch their respective RFID sensingtransmit signals.

A RFID object, such as a RFID tag, in the vicinity of the first orsecond RFID sensing transmit antenna 1036, 1037 generates a RFID sensingreturn signal. The RFID sensing return signal impinges on and excitesthe appropriate first or second RFID sensing receive antenna 1038, 1039,respectively, to provide a RFID sensing receive signal. An output of thefirst or second RFID sensing receive antenna 1038, 1039 is provided tothe first or second RFID receive conditioning filter 1033, 1034,respectively. The first or second RFID receive conditioning filter 1033,1034 sufficiently attenuates the out-of-band energy and provides aproper impedance match between the first or second RFID sensing receiveantenna 1038, 1039 and the first or second RFID sensing receiveamplifier 1025, 1026, respectively.

The first or second RFID sensing receive amplifier 1025, 1026 amplifiesthe small RFID sensing receive signal to a level sufficient forprocessing and provides an amplified RFID sensing receive signal to theRFID sensing receive selector switch 1027, which is controlled by thecontrol and processing subsystem 1040. The control and processingsubsystem 1040 selects the appropriate reception path through the RFIDsensing receive selector switch 1027 for input to the RFID sensing ADC1028, based on the excitation signal transmitted. The RFID sensing ADC1028 provides a RFID sensing digital signal, proportional to the RFIDsensing receive signal, to the control and processing subsystem 1040,which determines if the RFID sensing receive signal has a signaturerepresenting a presence of a RFID object in the vicinity of the RFIDsensing antenna 1035.

Turning now to FIG. 11, illustrated is a system diagram of analternative embodiment of an interrogator, generally designated 1100,constructed in accordance with the principles of the present invention.The interrogator 1100 includes a metal sensing subsystem 1105, a RFIDsensing subsystem 1110, a metal and RFID sensing antenna diplexer 1112,a metal and RFID sensing integrated antenna 1114, a control andprocessing subsystem 1115, a communications subsystem 1125, a userinterface 1130, a position sensor 1135 and a power source 1140.

The interrogator 1100 is similar to the interrogator 900 of FIG. 9wherein the metal and RFID sensing antenna diplexer 1112 has replacedthe metal sensing antenna interface 906 and the RFID sensing antennainterface 911. Additionally, the metal and RFID sensing integratedantenna 1114 has replaced the metal sensing antenna 907 and the RFIDsensing antenna 912. General operation of the interrogator 1100 is alsosimilar to the operation of the interrogator 900 of FIG. 9.

However, the interrogator 1100 employs the metal and RFID sensingantenna diplexer 1112 between the transmit and receive paths associatedwith both the metal sensing and RFID sensing subsystems 1105, 1110. Themetal and RFID sensing antenna diplexer 1112 accommodates the frequencyselecting and impedance matching functions. Similarly, the metal andRFID sensing integrated antenna 1114 is also employed in both thetransmit and receive paths associated with both the metal sensing andRFID sensing subsystems 1105, 1110. A more detailed discussion of themetal and RFID sensing antenna diplexer 1112 and the metal and RFIDsensing integrated antenna 1114 are presented below with respect to FIG.12.

Turning now to FIG. 12, illustrated is a block diagram of anotherembodiment of an interrogator, generally designated 1200, constructed inaccordance with the principles of the present invention. Theinterrogator 1200 includes a metal sensing subsystem 1205, a RFIDsensing subsystem 1210, a metal and RFID sensing antenna diplexer 1215,a metal and RFID sensing integrated antenna 1225 and a control andprocessing subsystem 1230.

The metal and RFID sensing antenna diplexer 1215 includes a metalsensing transmit conditioning filter 1216, a metal sensing receiveconditioning filter 1217, a metal sensing diplexer switch 1222, firstand second RFID sensing transmit conditioning filters 1218, 1219, firstand second RFID sensing receive conditioning filters 1220, 1221 andfirst and second RFID sensing diplexer switches 1223, 1224. The metaland RFID sensing integrated antenna 1225 includes a metal sensingtransmit/receive antenna 1226 and first and second RFID sensingtransmit/receive antennas 1227, 1228.

Operation of the metal sensing subsystem 1205, the RFID sensingsubsystem 1210 and the control and processing subsystem 1230 areanalogous to the metal sensing subsystem 1005, the RFID sensingsubsystem 1020 and the control and processing subsystem 1040 as wasdiscussed with respect the interrogator 1000 of FIG. 10. Alternatively,the metal and RFID sensing subsystems 1205, 1210 may be integrated intoa sensing subsystem that provides a signal or a plurality of signalshaving at least one of a metal signature representing a presence of ametal object and a RFID signature representing a presence of a RFIDobject.

However, the interrogator 1200 employs the metal and RFID sensingintegrated antenna 1225, which shares a common antenna betweenassociated transmit and receive signals. For example, the metal sensingtransmit/receive antenna 1226 is coupled to both the metal sensingtransmit conditioning filter 1216 and the metal sensing receiveconditioning filter 1217 via the metal sensing diplexer switch 1222.Similarly, the first and second RFID sensing transmit/receive antennas1225, 1228 are coupled through the first and second RFID sensingdiplexer switches 1223, 1224 to their corresponding RFID sensingconditioning filters.

Generally, the diplexer switches are configured as conventionalthree-port devices so as to provide low loss paths for excitationsignals proceeding from the transmit amplifiers to the antennas andcorrespondingly to provide low loss paths for incoming signals from theantennas to the receiving amplifiers. In time domain configurations,these may be accomplished by simple switching or gating. In continuousmode configurations, this may be accomplished by properly phasingsignals so that they are in-phase when traveling to a desired port andout-of-phase when traveling to an undesired port.

The metal and RFID sensing integrated antenna 1225 provides a suitablematch to both launch a transmit signal and accept a receive signalassociated with the metal and RFID sensing functions. The individualantennas may consist of single elements or may themselves be complex innature with multiple elements. The antennas may be partially shielded soas to inhibit transmitted and received radiation to and from unwanteddirections. For example, an antenna being passed over a patient orportion of the operating room such as a back table or MAYO stand, shouldideally have maximum sensitivity in the direction and vicinity of thepatient and maximum attenuation in all other directions.

Turning now to FIG. 13, illustrated is a block diagram of an embodimentof a control and processing subsystem, generally designated 1300,constructed in accordance with the principles of the present invention.The control and processing subsystem 1300 includes a digital signalprocessor 1305 employing a frequency control crystal 1310, a bootstrapmemory 1315, a flash memory 1320, a random access memory 1325, and aninput/output interface 1330.

The control and processing subsystem 1300 provides the digital signalprocessing functions, the signal generating functions, the controlfunctions and the input and output interface functions associated withan interrogator. The digital signal processor 1305 may be embodied as asingle integrated circuit, or as a group of integrated circuitsperforming this role. All transmit signals are generated within thedigital signal processor 1305 which also includes a signal synthesizingfunction. The frequency control crystal 1310 provides proper timing forthe signal synthesizing function.

The bootstrap memory 1315 is a non-volatile read-only memory thatcontains a basic software program to enable the interrogator to powerup, accept commands from the keyboard, display diagnostics, and allowdata ports to be used. In the case of a software-related system failure,the bootstrap system 1315 allows the interrogator to recover (i.e.,reboot). It also possesses basic system diagnostics which may be runindependently of whatever software has been loaded.

The flash memory 1320 is a non-volatile random access memory, where thecurrent operating system and program of the interrogator is loaded. Thecontents of the flash memory 1320 may be changed, updated and checked bydiagnostics and programs contained in The bootstrap memory 1315. Forexample, diagnostics exist within the bootstrap memory 1315 to test therandom access memory 1325. The input/output interface 1330 is a portionof the control and processing subsystem 1300 that accesses all othernecessary portions as well as external ports of the interrogator,wherein the collection of interface connections 1335 may be consideredtypical.

The data I/O port of the collection of interface connections 1335 allowsspecific software releases or upgrades to be loaded into aninterrogator, either wirelessly or using a wireline. In this manner, thecharacteristics of the interrogator may be easily changed or upgraded asnecessary or appropriate. The software defined architecture enables thiscapability since all signal processing decisions and signal generationinitiation occurs within the control and processing subsystem 1300.

Similarly, this architecture permits upgrading of existing algorithmsand incorporation of new algorithms for existing RFID tag and metaldetection without hardware modifications. Therefore, the interrogatormay be employed as substantially a universal interrogator that iscapable of adaptation to read multiple versions of RFID tags fromvarious manufacturers, including future-developed RFID tags. Of course,this may also include metal detection improvements and additions, aswell.

Although the embodiments this invention presented have concentrated onthe detection and monitoring of disposable and non-disposable medicalequipment, alternative embodiments and future applications outside themedical field are envisioned. These applications include integrating thedetection of multiple disparate objects within a single system and theintegration of disparate observables into a single integrating filter.Also included are the real-time integration of observables with multipledatabases, and the real-time offloading of portions of the signalprocessing from the interrogator.

Alternative embodiments may include added detection range, increaseddetection sensitivity in hostile environments, increased detectionintegrity, real-time versatility in dynamically selecting what is to bedetected, and simultaneous universal detection of multiple types of RFIDtags and metallic objects, often operating at disparate frequencies.These applications and embodiments may encompass, for example, inventorymanagement, supply chain management, and security.

In summary, embodiments of the present invention employing aninterrogator, a method of discerning a presence of at least one of ametal and a RFID object, and an interrogation system employing the samehave been presented. The interrogator and the interrogation system maybe operated in either an autonomous mode or an integrated mode. In theautonomous mode of operation, the control and processing subsystemautonomously accomplishes the operation of the interrogator by providinganalysis algorithms and performing functions needed to discern thepresence of metal and RFID objects. Alternatively, the integrated modeof operation may employ a computer system, either wirelessly or througha wired interface, to support the control and processing subsystem indiscerning the presence of metal and RFID objects. It also may employthe integration of additional sensors such as inertial sensors. Theintegrated mode of operation typically allows a more extensiveutilization of databases and algorithms to be employed than in theautonomous mode of operation.

Although the present invention has been described in detail, thoseskilled in the art should understand that they can make various changes,substitutions and alterations herein without departing from the spiritand scope of the invention in its broadest form.

1. An interrogation system, comprising: a sensing subsystem configuredto provide a signal having a signature representing a presence of anobject located within or proximate a person; a control and processingsubsystem configured to discern a presence of said object from saidsignal; and an inertial position sensor configured to provide a locationof said object with respect to said person.
 2. The interrogation systemas recited in claim 1 wherein said sensing subsystem is a radiofrequency identification (RFID) sensing subsystem configured to providea signal having a signature representing a presence of an RFID objectlocated within or proximate said person, said control and processingsubsystem configured to discern a presence of said RFID object from saidsignal and said inertial position sensor configured to provide alocation of said RFID object with respect to said person.
 3. Theinterrogation system as recited in claim 1 wherein said sensingsubsystem is a metal sensing subsystem configured to provide a signalhaving a signature representing a presence of a metal object locatedwithin or proximate said person, said control and processing subsystemconfigured to discern a presence of said metal object from said signaland said inertial position sensor configured to provide a location ofsaid metal object with respect to said person.
 4. The interrogationsystem as recited in claim 1 further comprising at least one antennaconfigured to cooperate with said sensing subsystem to provide saidsignal having said signature representing said presence of said objectlocated within or proximate said person.
 5. The interrogation system asrecited in claim 1 further comprising at least one antenna located nearsaid inertial position sensor and configured to cooperate with saidsensing subsystem to provide said signal having said signaturerepresenting said presence of said object located within or proximatesaid person.
 6. The interrogation system as recited in claim 1 furthercomprising an antenna configured to cooperate with said sensingsubsystem to provide said signal having said signature representing saidpresence of said object located within or proximate said person, whereinat least one of said sensing subsystem, said control and processingsubsystem, said inertial position sensor and said antenna assembly islocated in a portable interrogator.
 7. The interrogation system asrecited in claim 1 wherein said control and processing subsystem isconfigured to employ multiscan, coherent signal processing.
 8. Theinterrogation system as recited in claim 1 wherein said control andprocessing subsystem includes an adaptive integrating filter and isconfigured to coordinate a processing of said signal in conjunction withone of an observable and data to discern a presence of said object. 9.The interrogation system as recited in claim 1 wherein said control andprocessing subsystem is located in a computer system in communicationwith said sensing subsystem.
 10. The interrogation system as recited inclaim 1 further comprising at least one position marker located on orproximate a person configured to cooperate with said inertial positionsensor to provide a location of said object with respect to said person.11. The interrogation system as recited in claim 10 wherein said personis located in an operating room of a medical facility and said at leastone position marker is located on at least one of: said person, a backtable, a Mayo stand, a ring stand, and a kick bucket.
 12. Theinterrogation system as recited in claim 1 further comprising a braceletattached to and including information about said person.
 13. Theinterrogation system as recited in claim 1 further comprising at leastone calibration marker located about said person configured to calibratea type and sensitivity of interrogation associated with saidinterrogation system.
 14. The interrogation system as recited in claim 1wherein said sensing subsystem is located in an operating room of amedical facility on one of: a back table, a Mayo stand, and a ringstand.
 15. The interrogation system as recited in claim 1 furthercomprising another sensing subsystem configured to provide a signalhaving a signature representing a presence of an object located withinor proximate said person.
 16. A method of operating an interrogationsystem, comprising: providing a signal having a signature representing apresence of an object located within or proximate a person; discerning apresence of said object from said signal; and providing a location ofsaid object with respect to said person with an inertial positionsensor.
 17. The method as recited in claim 16, further comprising:providing a signal having a signature representing a presence of one ofan RFID and a metal object located within or proximate said person;discerning a presence of one of said RFID and metal object from saidsignal; and providing a location of one of said RFID and metal objectwith respect to said person in accordance with said inertial positionsensor.
 18. The method as recited in claim 16 wherein discerning employsmultiscan, coherent signal processing.
 19. The method as recited inclaim 16 wherein said providing said location includes employing atleast one position marker located on or proximate a person configured tocooperate with said inertial position sensor to provide said location ofsaid object with respect to said person.
 20. The method as recited inclaim 16 further comprising locating at least one calibration markerabout said person configured to calibrate a type and sensitivity ofinterrogation associated with said interrogation system.